[A case of chronic obstructive pulmonary disease associated with central alveolar hypoventilation diagnosed by...

We report a case of chronic obstructive pulmonary disease associated with central alveolar hypoventilation diagnosed by exercise test. A 61-year-old man with chronic obstructive pulmonary disease was admitted to our hospital because of respiratory failure caused by bacterial pneumonia. After recovery from pneumonia, we examined his functional ventilatory response to incremental exercise. Exercise was discontinued because of his maximal target heart rate, and there was no complaint of dyspnea throughout the exercise test. Although the patient had enough ventilatory reserve during exercise (VEmax/MVV = 50%), there was a marked progressive retention of carbon dioxide disproportionate to the extent of his air flow obstruction. Moreover the patient was able to reduce the carbon dioxide tension to a subnormal level by voluntary hyperventilation, and his ventilatory response to carbon dioxide and mouth occlusion pressure at rest was significantly diminished as compared with normal subjects. These findings suggest that this patient has several features compatible with central alveolar hypoventilation. Exercise test was useful for the diagnosis as well as exercise prescription because the patient could develop dangerous hypoxemia without alarming symptoms like dyspnea.